Can a Low-Calorie Diet Reverse Diabetes?

In study, 40 percent of adults with type 2 diabetes achieved a fasting glucose level of less than 126mg/dL.(7mmol/L) after eight weeks on a very low-calorie diet.

In this small study of 30 people with type 2 diabetes, researchers found that eight weeks on a very low calorie diet of around 600 to 700 calories a day, followed by a less radical six-month weight control diet, led to significant improvement in blood glucose levels in 12 people.

Lead researcher, Roy Taylor, MD, FRCP, professor of medicine and metabolism at Newcastle University in the United Kingdom, had previously led a similar study in 2011, which suggested calorie restriction might reverse diabetes. However, the 2011 study lasted only eight weeks. For the current study, volunteer participants spent eight weeks on the extremely restricted diet and then switched to a less restrictive weight control plan for six months. Study participants were all type 2 diabetes patients, with time since diagnosis ranging from 6 months to 23 years, and were overweight or obese. Participants lost an average of about 30 pounds and maintained the loss throughout the six-month period.

The specifics of the diet were: for 8 weeks, 3 diet shakes and a small amount of non-starchy vegetables, totaling between 600 and 700 calories a day; for the 6-month weight control period, volunteers were seen once a month and supported with an individualized weight maintenance program. To keep weight steady after the weight loss, they were eating around one third less than before the study.

Tests administered to the participants during the six-month weight control period were HbA1c, insulin sensitivity, glucose production in the liver, and measurements of fat in the liver, pancreas, and body. The tests found that 12 people had glucose levels below the usual cutoff for diabetes. While many of the study participants had diabetes of long duration, ranging from 8 – 23 years, those whose glucose levels dropped below the diabetes cutoff tended to be those whose diabetes was at the lower end of duration: under 10 years.

Lead researcher Roy Taylor, MD, FRCP, professor of medicine and metabolism at Newcastle University in the United Kingdom, commented: “What we have shown is that it is possible to reverse your diabetes, even if you have had the condition for a long time, up to around 10 years. If you have had the diagnosis for longer than that, then don’t give up hope – major improvement in blood sugar control is possible.”

Taylor noted that the study supported the researchers’ theory of a “Personal Fat Threshold”: “If a person gains more weight than they personally can tolerate, then diabetes is triggered, but if they then lose that amount of weight, then they go back to normal. Individuals vary in how much weight they can carry without it seeming to affect their metabolism – don’t forget that 70% of severely obese people do not have diabetes.”

The researchers concluded that the weight loss through the low calorie diet removed excess fat from the pancreas, allowing beta cells to return to producing normal levels of insulin. They noted, however, that not all participants could experience this response, due to the fact that some had insufficient insulin production from the pancreas at the start of the study.

While the researchers viewed the results as promising, noting that they contributed to the understanding of type 2 diabetes as a metabolic syndrome potentially reversible through weight loss, they noted that it was not yet clear whether long-term reversal would be achievable in the general population of type 2 diabetes patients. While losing weight and keeping it off might be a way for some to reverse their condition through diet alone, not all might be willing to make the changes necessary.

While these results are encouraging, it is important to note that this was a small, uncontrolled, non-randomized clinical trial; further study is needed. A larger trial of 280 patients is underway, funded by Diabetes UK.

Practice Pearls:

The results suggest that a lower caloric diet coupled with skills that promote behavior change may improve glucose control in type 2 diabetes

A very low-calorie diet can help adults with type 2 diabetes reverse their diabetes, and those who keep their weight down may remain free of diabetes.

Many people with type 2 diabetes may not be willing to make the changes necessary to improve their diabetes.